Field emission type cold cathode device, manufacturing method thereof and vacuum micro device

ABSTRACT

A field emission type cold cathode device comprises a substrate, and a metal plating layer formed on the substrate, the metal plating layer contains at least one carbon structure selected from a group of fullerenes and carbon nanotubes, the carbon structure is stuck out from the metal plating layer and a part of the carbon structure is buried in the metal plating layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2000-098026, filed Mar. 31,2000, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention concerns a field emission type cold cathodedevice, a manufacturing method thereof and a vacuum micro device usingthe field emission type cold cathode device.

As field emission type cold cathode device, one using fullerene orcarbon nanotube for emitter has been proposed (for instance, Jpn. Pat.Appln. KOKAI Publication No. 10-149760). Fullerene and carbon nanotubesallow to lower the driving voltage and improve the field emissionefficiency as their tip curvature radius is small. In addition, they canoperate at a low vacuum degree, as they are influenced little by theatmosphere dependency or residual gas.

Concerning methods for forming the aforementioned field emission typecold cathode device, a method for dispersing fullerene or carbonnanotube in an organic solvent, applying and contact bonding on asubstrate, a method for directly depositing fullerene or carbon nanotubeon a substrate, a method for dispersing fullerene or carbon nanotube ina thick film paste, printing and annealing under a high temperature(about 500 to 800° C.), or the like are proposed.

However, when fullerene or carbon nanotube is contact bonded ordeposited on a substrate, the adherence of fullerene or carbon nanotubeis weak, and it is peeled off easily by a strong electric field appliedto the emitter. Besides, when fullerene or carbon nanotube is formed byprinting, the performance lowers or deteriorates due to high temperatureannealing.

In addition, in contact boding, the patterning for cathode lineformation is extremely difficult, because carbon is highlychemical-resistant, and etching is difficult. Otherwise, in a depositionmethod by CVD method or the like, catalyst of transition metal isrequired, and signal delay or the like is produced easily, becausefullerene or carbon nanotube is required to be atomized, resulting inhigh resistance value. In the printing method also, signal delay or thelike is produced easily, because of high film resistance, and inaddition, difficulty of forming a thick film and, consequently, lowresistance wiring.

Thus, field emission type cold cathode devices using fullerene or carbonnanotube as emitter have been proposed, conventionally, they were notnecessarily sufficient in respect of reliability or performance.

BRIEF SUMMARY OF THE INVENTION

An aspect of the present invention intends to solve the aforementionedproblems, and has an object to improve the reliability or performance ofa field emission type cold cathode device using fullerene or carbonnanotube for emitter.

A field emission type cold cathode device according to a first aspect ofthe present invention, comprises a substrate; and a metal plating layerformed on the substrate; wherein the metal plating layer contains atleast one carbon structure selected from a group of fullerenes andcarbon nanotubes, the carbon structure is stuck out from the metalplating layer and a part of the carbon structure is buried in the metalplating layer.

The field emission type cold cathode device further may comprise aconductive layer formed between the substrate and the metal platinglayer.

In the field emission type cold cathode device, the metal plating layermay be selected from a group of nickel, chromium and copper.

In the field emission type cold cathode device, the metal plating layermay be formed by either electroplating processing or electroless platingprocessing.

According to an aspect of the present invention, the metal layer isfirmly fixed to the support substrate, and further fullerene or carbonnanotube is firmly fixed to the metal plating layer as a part offullerene or carbon nanotube is buried in the metal plating layer. Inother words, among fullerene or carbon nanotube contained in the metalplating layer, fullerene or carbon nanotube having protrusions(functioning substantially as electron emission section) on the surfaceof the metal plating layer is firmly fixed to the metal plating layer,because the portion under the protrusion is buried in the metal platinglayer. Consequently, an adhesion resistance that can resist sufficientlyagainst a strong electric field applied to the emitter can be obtained,and it becomes possible to obtain a high performance field emission typecold cathode device excellent in field emission stability.

Here, the metal plating layer (metal plating film) obtained by platingprocessing is fine, and better in conductivity and hardness, compared tothe metal film obtained by spattering method or printing method. As forthe conductivity, the metal plating film is almost equivalent to bulkmetal (equal or superior to about 99% of bulk metal conductivity), andlower in resistance compared to spattered metal film (about 30 to 90%),and thick film printed metal film (about 10 to 20%). Concerning thehardness, when compared in Vickers harness and Brinell harness, themetal plating film is almost equivalent to the bulk metal (equal orsuperior to about 90%) and can be about 10 times in some cases, andextremely harder than the spattered metal film and thick film printedmetal film.

Even made thicker, the metal plating film hardly peels off ordeteriorates in film quality; therefore, a film further thicker than thefilm thickness limit of the spattered metal film (about 1 to 2 μm) canbe formed.

Further, the metal plating film can be formed in an almost eventhickness, event if the surface to be plated is rough. For example, themetal plating film formed on the cathode line surface can make the filmthickness almost equivalent at the top and the side of the cathode line.

Also, as the plating processing is performed at a low temperature, themetal plating film allows to obtain an emitter with less performanceloss or deterioration. In addition, as it allows to obtain a highconductive film and to increase the thickness, the resistance of thecathode line can be lowered, and signal delay or the like can besuppressed. Moreover, as patterning is easy, the cathode line can becreated easily.

Besides, when a convex emitter structure is formed using metal platingfilm, the electron emission point can be fixed easily, as electric fieldis concentrated to the convex tip section. In addition, as convex metalplating layer can be separated easily from the mold by lubricatingeffect of fullerene of the like, mold wear or damage can be suppressedeven when the mold is used repeatedly.

Moreover, in the field emission type cold cathode device, the carbonnanotubes may have a conductive material inside. The conductive materialis preferably a content of a plating liquid used for forming the metalplating layer. The conductive material is preferably selected from Mo,Ta, W, Ni, Cr, Fe, Co, Cu, Si, LaB₆, AlN, GaN, carbon, graphite anddiamond.

Thus, the formation of the conductive material section inside a hollowstructure that the carbon nanotube has, makes the conductive materialwork as core material, allowing to increase the carbon nanotubemechanical resistance. Especially, the formation of conductive materialsection with a content of plating liquid used to form the metal platinglayer, allows to perform plating and forming the conductive materialsection in parallel, and consequently, to simplify the process.

Here, in the field emission type cold cathode device, the metal platinglayer may contain additive material for increasing resistance of themetal plating layer. The additive material is preferably selected fromboron, phosphorus and polytetrafluoroethylene (PTFE). The additivematerial, blended (dispersed preferably) simple or in the form ofcompound in the plating liquid, can be contained easily in the metalplating layer, when the metal plating layer is formed by plating.

When the emitter tip is different in curvature radius, shape or thelike, the field emission characteristics become uneven because ofdifferent electric field strength distribution. As mentioned above, whenthe resistance of the metal plating layer is increased by includingadditive material in the metal plating layer, the voltage drops due tothe metal plating layer. As the result, even when the emitter tip isdifferent in curvature radius, shape or the like, the electric fieldstrength distribution of the emitter tip is evened by so-calledresistive ballasting effect, allowing to improve considerably the fieldemission stability and evenness.

A vacuum micro device according to a second aspect of the presentinvention, comprises: a substrate; a metal plating layer formed on thesubstrate, the metal plating layer containing at least one carbonstructure selected from a group of fullerenes and carbon nanotubes, andthe carbon structure being stuck out from the metal plating layer and apart of the carbon structure being buried in the metal plating layer;and an electrode disposed separately from the substrate, the electrodeapplied a higher electrical potential than an electrical potentialapplied to the metal plating layer.

The vacuum micro device preferably further comprises a conductive layerformed between the substrate and the metal plating layer.

A vacuum micro device according to a third aspect of the presentinvention, comprises a first substrate; a conductive layer formed on thefirst substrate; a metal plating layer formed on the conductive layer,the metal plating layer containing at least one carbon structureselected from a group of fullerenes and carbon nanotubes, and the carbonstructure being stuck out from the metal plating layer and a part of thecarbon structure being buried in the metal plating layer; a secondsubstrate opposed to the first substrate; an electrode formed on thesecond substrate, the electrode applied a higher electrical potentialthan an electrical potential applied to the metal plating layer; and aluminescent material formed on the electrode

The vacuum micro device preferably further comprises an insulation layerformed on the substrate; and a gate electrode formed on the insulationlayer and between the metal plating layer and the electrode.

A manufacturing method of field emission type cold cathode deviceaccording to a fourth aspect of the present invention, comprisesimmersing a substrate in a plating liquid containing at least one carbonstructure selected from a group of fullerenes and carbon nanotubes; andforming a metal plating layer on the conductive layer, wherein thecarbon structure is stuck out from the metal plating layer and a part ofthe carbon structure is buried in the metal plating layer.

The manufacturing method preferably further comprises forming aconductive layer on a substrate before immersing the substrate.

A manufacturing method of field emission type cold cathode deviceaccording to a fifth aspect of the present invention, comprises forminga conductive layer on a first substrate having concaves; immersing thefirst substrate in a plating liquid containing at least one carbonstructure selected from a group of fullerenes and carbon nanotubes;forming a metal plating layer on the conductive layer, the carbonstructure being stuck out from the metal plating layer and a part of thecarbon structure being buried in the metal plating layer; pressing asecond substrate to the first substrate sandwiching the metal platinglayer; and removing the first substrate from the second substrateleaving the metal plating layer on the second substrate.

In the manufacturing methods of the field emission type cold cathodedevice, the plating processing is preferably one of electroplatingprocessing and electroless plating processing. Especially, when themetal plating layer is formed by electroplating, the carbon nanotube caneasily be oriented vertically along the line of electric force.Consequently, the proportion of carbon nanotube oriented vertically canbe increased, and the field emission efficiency and the evenness offield emission can be enhanced.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1A to FIG. 1D show schematically the manufacturing process of fieldemission type cold cathode device according to a first embodiment of thepresent invention;

FIG. 2A and FIG. 2B show schematically the structure of essential partof the field emission type cold cathode device shown in FIG. 1C and FIG.1D;

FIG. 3 shows schematically the structure of essential part of a variantof the field emission type cold cathode device shown in FIG. 1C;

FIG. 4A to FIG. 4C show schematically the manufacturing process of fieldemission type cold cathode device according to a second embodiment ofthe present invention;

FIG. 5A to FIG. 5D show schematically the manufacturing process of fieldemission type cold cathode device according to a third embodiment of thepresent invention;

FIG. 6A to FIG. 6C show schematically the manufacturing process ofvacuum micro device according to a fourth embodiment of the presentinvention;

FIG. 7 shows schematically an example of flat type image display deviceaccording to a fifth embodiment of the present invention; and

FIG. 8 shows schematically another example of flat type image displaydevice according to a fifth embodiment of the present invention.

FIG. 9 shows schematically another example of flat type image displaydevice according to a fifth embodiment of the present invention.

FIG. 10A to FIG. 10D show schematically the manufacturing process offield emission type cold cathode device according to a sixth embodimentof the present invention;

FIG. 11A and FIG. 11B show schematically the manufacturing process ofvacuum micro device according to a seventh embodiment of the presentinvention; and

FIG. 12A to FIG. 12C show schematically the manufacturing process ofvacuum micro device according to an eighth embodiment of the presentinvention;

DETAILED DESCRIPTION OF THE INVENTION

Now the embodiments of the present invention will be described referringto drawings.

Embodiment 1

FIG. 1A to FIG. 1D show schematically the manufacturing process of fieldemission type cold cathode device according to a first embodiment of thepresent invention.

First, as shown in FIG. 1A, a cathode line 12 is formed on a glasssubstrate (support substrate) 11. Considering signal delay in a largefield emission type display, Ni plating film allowing to obtain a highconductive film as formed with a thickness of about 2 μm, as metal filmto be the cathode line 12.

Next, Ni—B—P base electroless plating liquid 13 a, adjusted to aboutPH5, is prepared by dissolving about 25 g of nickel sulfate, about 40 gof sodium hypophosphite, about 10 g of sodium acetate, about 10 g ofsodium citrate, and about 30 g of boric acid in about 1 litter ofdistillated water. About 50 g of fullerene C₆₀ or carbon nanotube aremixed in this plating liquid.

Both fullerene and carbon nanotube are carbon allotropies, and basicallyof the homogeneity. An extremely long fullerene of specific form becomescarbon nanotube. The basic type of fullerene is C₆₀ composed of6-membered rings of carbon and 5-membered rings of carbon, having adiameter of about 0.7 nm. C₆₀ has a structure wherein sp2 orbitalhybridization carbon atoms are disposed at all of apexes of a 32-hedronobtained by cutting off all apexes of 12 pyramids in a regular20-hedron.

As for fullerene, except for C₆₀, higher order fullerenes having morethan 60 carbons, such as C₇₀, C₇₆, C₈₂, C₈₄, C₉₀, C₉₆, . . . , C₂₄₀,C₅₄₀, C₇₂₀ and so on exist substantially without limit, and of coursethey may also be used. In addition, as the inside of fulleren is hollow,onion type fullellenes wherein several layers of lower order fullereneare packed in a higher order fullerene exist, and they may be used.Moreover, fullerenes encapsulating metal in the cavity, such as La@C₆₀,La@C₇₆, La@C₈₄, La₂@C₈₀, Y₂@C₈₄, Sc₃@C₈₂, or the like may also be used.Further, hetero fulluerene incorporating atoms other than carbon, suchas N, B, Si in the skeletal portion of fulleren may be used. Thesefullerenes can be obtained by evaporating carbon by means of laserirradiation, arc discharge or resistance heating to graphite, cooling,reacting and condensing evaporated carbon passing through helium gas,and collecting condensed carbon by a collection member.

Next, plating solution 13 a prepared as mentioned above is stirred in aplating vessel 14. Thereafter, as shown in FIG. 1B, the glass substrate11 on which a cathode line 12 is formed is immersed in the platingsolution 13 a, and electroless plating is performed while keeping thetemperature of the plating solution 13 a at about 80° C.

Thus, the glass substrate is immersed in the plating solution 13 a forabout 3 minutes. As the result, fullerene or carbon nanotube hasprecipitated down to contact with the cathode line 12, and a Ni—B—P baseelectroless plating layer (metal plating layer 15) containing fullerene17 or carbon nanotube 16 is formed on the cathode line 12 with athickness of about 3 μm as shown in FIG. 1C (for carbon nanotube) orFIG. 1D (for fullerene). The using of plating method allows to obtain ametal plating layer 15 of a film thickness almost equivalent at the topand the side of the cathode line 12. Besides, on the glass substrate 11between adjacent cathode lines 12, the metal plating layer 15 is formedscarcely, or if formed, peeled off easily under the ultrasonicprocessing, because of weak adherence of the metal plating layer 15.After being rinsed with water and dried, a patterned field emission typecold cathode can be obtained.

FIG. 2A (for carbon nanotube) and FIG. 2B (for fullerene) showschematically the structure of essential parts of the metal platinglayer 15 containing fullerene 17 or carbon nanotube 16, formed by themethod mentioned above.

As shown in FIG. 2A and FIG. 2B, among a number of fullerene 17 orcarbon nanotubes 16 existing on the cathode line integrated with themetal plating layer 15, some fullerene 17 or carbon nanotubes 16protrude outside the metal plating layer 15. Portions protruding outsidethe metal plating layer 15 in this way function substantially aselectron emission portions. The lower portion of the fullerene 17 orcarbon nanotubes 16 having portions protruding outside the metal platinglayer 15 are buried in the metal plating layer 15. Therefore, thesefullerene 17 or carbon nanotubes 16 are fixed firmly to the metalplating layer 15, assuring a sufficient adhesion resistance.

In FIG. 2A and FIG. 2B, a thin metal plating layer 15 may well be formedalong the outer periphery of fullerene 17 or carbon nanotubes 16protruding outside the metal plating layer 15.

Field emission characteristics of the field emission type cold cathodemanufacture as mentioned above are measured; the metal plating layer 15holds a firm adherence and does not peel off against a strong electricfield of equal or superior to about 10⁷ V/cm applied to the emitter tip,and stable field emission characteristics can be obtained.

Further, the addition of impurities such as boron or phosphorus in themetal plating layer 15 permits the metal plating layer 15 to have acertain magnitude of resistance value. Therefore, the current emissionstability is improved by about 20 to 30%, and the even field emissioncharacteristics in the plane is also improved by the so-called resistiveballasting effect.

Also, the tip curvature radius can be reduced considerably compared tothe Mo emitter manufactured by the rotary evaporation method. To be morespecific, it can be reduced from about 70 to 300 nm to about 1 to 30 nm.As the result, the driving voltage also can be reduced form about 100Vto about 7V. On the other hand, when the vacuum degree lowers from about10⁻⁹ torr to about 10⁻⁷ torr, the emission current value is reduced toequal or inferior to about 1/10, and the current variation increases byequal or superior to several hundreds percents for the Mo emittermanufactured by the rotary evaporation method, but they vary hardly forthe present embodiment.

Thus, in this embodiment, fullerene or carbon nanotube are dispersed inthe plating liquid to perform the plating processing, allowing fullereneor the like to precipitate and come into contact with the cathodesurface, forming a metal plating layer. Therefore, fullerene or the likeis fixed firmly to the metal plating layer as well as the metal platinglayer is firmly fixed to the cathode. As a result, a highly adhesiveemitter that can resist a strong electric field is obtained, and thefield emission stability can be enhanced.

Moreover, in this embodiment, as the plating processing is performed ata low temperature equal or inferior to about 100° C., an emitter can bemanufactured with little damage.

In addition, conventionally, when the emitter tip was different incurvature radius, shape or the like, the field emission characteristicsbecame remarkably uneven, because of different electric field strengthdistribution. In this embodiment, a Ni—B—P base resistive plating layercontaining impurities in the metal plating layer and presenting aresistance value higher than the Ni plating layer is used. Consequently,as the potential lowers due to resistive plating layer, even when theemitter tip is different in curvature radius, shape or the like, theelectric field strength of the emitter tip lowers substantially by theresistive ballasting effect, and field emission stability and evennessare improved.

Moreover, if the cathode line is formed on the glass substratebeforehand, the metal plating layer can be formed selectively on thecathode line, and the process can be simplified.

FIG. 3 shows schematically the structure of the essential part of avariant of the present embodiment.

In the example shown in FIG. 3, a filled layer 18 is formed as corematerial in the carbon nanotube 16 having a hollow structure. As thecarbon nanotube 16 has the hollows structure, plating liquid can beintroduced in the carbon nanotube 16 during the plating processing.Therefore, as shown in FIG. 3, the filled layer 18 can be formed in thecarbon nanotube 16 with substance contained in the plating liquid. Forexample, Ni, Cu or the like can be dissolved in the plating liquid andextracted inside the carbon nanotube 16, or material constituting thefilled layer may be dispersed in the plating liquid.

As for material composing the filled layer 18, it is preferable to usedconductive material such as Mo, Ta, W, Ni, Cr, Fe, Co, Cu, Si, LaB₆,AlN, GaN, carbon, graphite, diamond, or the like.

Having normally a large aspect ratio, the carbon nanotube decreases inits mechanical strength when it becomes longer. In this example, as theinside of the carbon nanotube 16 is filled with the filled layer 18constituting core material, the mechanical strength can be improved.Therefore, effects such as handling improvement in the manufacturingprocess, prevention of destruction due to electric field concentrationor the like can be obtained, allowing to obtain an emitter structureexcellent in reliability can be obtained.

It is also possible to form the filled layer previously in the carbonnanotube before forming the metal plating layer, or to form the filledlayer in the carbon nanotube after having formed the metal platinglayer. When the filled layer is formed previously in the carbon nanotubebefore forming the metal plating layer, the filling material may bemelted beforehand, and absorbed in the carbon nanotube. Also, the carbonnanotube may be filled with material constituting catalyst (for example,transition metal, or the like) when the carbon nanotube is formed by CVDmethod or the like.

Note that the structure as shown in FIG. 3 can equally be applied notonly to this embodiment, but also to other embodiments.

Second Embodiment

FIG. 4A to FIG. 4C show schematically the manufacturing process of fieldemission type cold cathode device according to a second embodiment ofthe present invention.

First, as shown in FIG. 4A, a cathode line 12 is formed on a glasssubstrate (support substrate) 11. Similarly to the first embodiment, inthe present embodiment, considering signal delay in a large fieldemission type display, Ni plating film allowing to obtain a highconductive film with a thickness of about 1 μm was formed, as metal filmbecoming the cathode line 12.

Next, an electroplating liquid 13 b, adjusted to about PH4, is preparedby dissolving about 600 g of nickel sulfamate, about 5 g of nickelchloride, about 30 g of sodium hypophosphite, and about 40 g of boricacid and about 1 g of saccharin in about 1 litter of distillated water.About 40 g of carbon nanotube are mixed in this plating liquid.

Plating solution 13 b prepared as mentioned above is stirred in aplating vessel 14 and thereafter, as shown in FIG. 4B, the glasssubstrate 11 on which a cathode line 12 is formed is immersed in theplating solution 13 b, and electroplating is performed while keeping thetemperature of the plating solution 13 b at about 50° C. Namely,electroplating is performed by applying current between the electrode 19and the cathode line 12.

Consequently, an Ni—B—P base resistive plating layer (metal platinglayer 15) containing carbon nanotube 17 is formed on the cathode line 12with a thickness of about 4 μm, as shown in FIG. 4C. The using ofplating method allows to obtain a metal plating layer 15 of a filmthickness almost equivalent at the top and the side of the cathode line12. On the glass substrate 11 between adjacent cathode lines 12, themetal plating layer 15 is formed scarcely, because of weak adherence ofthe metal plating layer 15.

Similarly to the first embodiment, in the present embodiment, as shownin FIG. 2A, the lower portion of the carbon nanotubes 17 having portionsprotruding outside the metal plating layer 15 are buried in the metalplating layer 15, assuring therefore a sufficient adhesion strength.

In the first embodiment, as the metal plating layer 15 is formed byelecroless plating, the carbon nanotubes 17 are oriented in variousdirections; however, in the embodiment, as the metal plating layer 15 isformed by elecroplating, the carbon nanotubes 17 can be oriented easilyin the vertical direction along the line of electric force.Consequently, the proportion of vertically oriented carbon nanotubes 17can be increased. The proportion of carbon nanotubes 17 oriented with anangle of about 70 to 110 degrees relative to the substrate surface isabout 50 to 100% under the normal condition, and the proportion can bechanged by adjusting electroplating conditions, or the like. Thus, inthe present embodiment, as the proportion of vertically oriented carbonnanotubes 17 can be increased, it is possible to enhance the fieldemission rate.

Field emission characteristics of the field emission type cold cathodemanufacture as mentioned above are measured; the metal plating layerholds a firm adherence and does not peel off against a strong electricfield of equal or superior to about 10⁷V/cm applied to the emitter tip,and stable field emission characteristics can be obtained.

Further, similarly to the first embodiment, the addition of impuritiessuch as boron or phosphorus in the metal plating layer permits toimprove the current emission stability by about 40 to 50%, and theevenness of the field emission in the plane is also improvedsubstantially by the so-called resistive ballasting effect.

In addition, the driving voltage can be reduced by about 3%, compared tothe non-oriented case, because the orientation has been improved.Besides, similarly to the first embodiment, the emission current valueand current fluctuation change scarcely when the vacuum degree isreduced.

In this embodiment also, effects similar to the first embodiment can beobtained and, in addition, as the metal plating layer is formed byelecroplating, the carbon nanotubes can be oriented easily in thevertical direction, and it becomes possible to enhance the fieldemission efficiency and the field emission evenness.

Third Embodiment

FIG. 5A to FIG. 5D show schematically the manufacturing process of fieldemission type cold cathode device according to a third embodiment of thepresent invention.

First, a mold substrate having a cavity sharpened at the bottom isprepared. As for a method for forming such cavity, there is a methodusing anisotropic etching of Si single crystal substrate as shown below.Note that it is also possible to form a mold having a similar cavity,using Ni or other metals, resin or glass or other materials.

As shown in FIG. 5A, SiO₂ film of about 0.1 μm in thickness is formed onthe p type Si single crystal substrate 31 of (100) crystal faceorientation by dry heat oxidation method, and a resist film is coatedthereon by spin coat method. Then, the resist film is exposed to lightand developed so as to obtain an opening pattern of about 1 μm square.Thereafter, SiO₂ film is etched by NH₄F.HF mixed solution. After theremoval of resist film, anisotropic etching is performed with KOHaqueous solution of about 30 wt % so that a reversed pyramid shapedcavity of about 0.7 μm in depth is formed on the surface of Si singlecrystal substrate 31. Next, after removal of SiO₂ film using NH₄F.HFmixed solution, SiO₂ film 32 is formed on the Si single crystalsubstrate 31 where the cavity is formed. In this example, this SiO₂ film32 is formed about 0.3 μm in thickness by wet heat oxidation method.

Then, as shown in FIG. 5B, Ni—B—P base electroless plating liquid asshown in the first embodiment is prepared, and about 50 g of fullereneC₆₀ is mixed and stirred in this electroless plating liquid. Thereafter,Ni—B—P base electroless plating layer of about 0.1 to 0.3 μm inthickness, containing fullerene, is formed on the SiO₂ film 32, byimmersing Si single crystal substrate 31 in the electroless platingliquid. Following this, Ni—B—P base electroplating liquid as shown inthe second embodiment is prepared, and about 50 g of fullerene C₆₀ ismixed and stirred in this electroplating liquid. Thereafter, Ni—B—P baseresistive plating layer of several μm in thickness, containingfullerene, is formed on the electroless plating layer, by immersing Sisingle crystal substrate 31 where the electroless plating layer isformed in the electroplating liquid. In this way, a metal plating layer33 including fullerene 34 made of laminated structure of electrolessplating layer and electroplating layer is formed.

Then, as shown in FIG. 5C, a glass substrate 35 is prepared as supportsubstrate, and the glass substrate 35 and the Si single crystalsubstrate 31 are adhered sandwiching the metal plating layer 33. Theymay be adhered using adhesives or the like, but the electrostaticadhesion method is used in this example.

Next, as shown in FIG. 5D, the Si single crystal substrate 31 wheresilicon oxide film 32 is formed is separated form the glass substrate 35to which the metal plating layer 33 is adhered, by dissolution, peelingoff or the like. In this way, an emitter section made of sharp metalplating layer 33 to which fullerene 34 is fixed is formed, and a fieldemission type cold cathode adapted for mass production is obtained. Notethat when the metal plating layer 33 covers the surface of fullerene 34,fullerene 34 may be exposed by removing the metal plating layer 33 withetching liquid or the like, or the metal plating layer 33 may remaincovering the fullerene 34 provided that desired characteristics can beobtained.

In this embodiment also, effects similar to the first and secondembodiment can be expected and, in addition, having a convex emitterform, the electric field is concentrated to the convex tip section. Asthe result, the electron emission point can be defined easily,facilitating the control and improving emitted current evenness in theplane, the evenness of emitted electron beam shape in the plane, or thelike. In addition, as convex metal plating layer can be separated easilyfrom the mold by lubricating effect of fullerene of the like, mold wearor damage can be suppressed even when the mold is used repeatedly.

Fourth Embodiment

FIG. 6A to FIG. 6C show schematically the manufacturing process ofvacuum micro device according to a fourth embodiment of the presentinvention. This vacuum micro device is manufactured by applying themanufacturing method of field emission type cold cathode using theplating method as shown in the first or second embodiment.

First, as shown in FIG. 6A, a cathode line 52 is formed on a glasssubstrate (support substrate) 51. Following this, an insulation layer 53made of SiO₂, or SiN or the like is formed on the glass substrate 51 andthe cathode line 52, and further, a gate electrode layer 54 made ofconductive material such as W is formed thereon. The insulation layer 53can be formed by electron beam evaporation method, spattering method,CVD method or others.

Next, as shown in FIG. 6B, the gate electrode layer 54 and theinsulation layer 53 are patterned by lithography technology to form gateelectrodes and gate wiring. At this time, the cathode line 52 is exposedin a cavity (concave portion) 55 surrounded by the insulation film 53and the gate electrode layer 54.

Next, as shown in FIG. 6C, a metal plating layer 56 containing carbonnanotube 57 is formed on the cathode line 52, by the plating processingas shown in the first or second embodiment.

Thus, a vacuum micro device using the carbon nanotube 57 fixed to themetal plating layer 56 as electron emission section is manufactured. Itgoes without saying, a metal plating layer 56 including fullerene inplace of carbon nanotube 57 may be formed.

Fifth Embodiment

FIG. 7 shows schematically an example of flat type image display device,as vacuum micro device according to a fifth embodiment of the presentinvention. This flat type image display device is manufactured byapplying the vacuum micro device as shown in the fourth embodiment(refer to FIG. 6). In other words, it is manufactured by applying themanufacturing method of field emission type cold cathode using theplating method as shown in the first or second embodiment.

In this flat type image display device, a plurality of gate lines madeof gate electrode layer 54 are arranged in the direction parallel to thepaper surface, and a plurality of cathode lines 52 are arranged in thedirection vertical to the paper surface. In addition, a group ofemitters made of a plurality of emitters 58 are disposed on the cathodeline 52, corresponding to the respective pixels.

A glass substrate (opposite substrate) 61 is disposed at a positionopposed to the glass substrate (support substrate) 51, and a vacuumdischarge space 62 is formed between two substrates. The intervalbetween two substrate 51 and 61 is maintained by a frame in theperiphery and a spacer 63. In addition, an anode electrode 64 and afluorescent element layer 65 are provided on the opposed surface of theglass substrate 61.

In this flat type image display device, pixel light-up and light-off areselected by arbitrarily setting the voltage between the gate electrode54 and the emitter 58 for respective pixel, through the gate line andcathode line. The selection of respective pixel is performed byso-called matrix driving. For instance, the desired pixel is selected byapplying a predetermined potential which is the selection signal to thecathode line, in synchronization with the application of a predeterminedpotential by sequentially selecting the gate line.

When a certain gate line and a certain cathode line are selected and apredetermined potential is applied to the respective lines, a group ofemitters at the intersection of the concerned gate line and cathode lineoperates. Electrons emitted from the group of emitters arrive at thefluorescent element layer 65 at the position corresponding to theselected group of emitter by the potential applied to the anodeelectrode 64, and lights up the fluorescent element layer 65.

FIG. 8 shows schematically another example of flat type image displaydevice according to this embodiment. This flat type image display deviceis also manufactured by applying the vacuum micro device as shown in thefourth embodiment (refer to FIG. 6). In other words, it is manufacturedby applying the manufacturing method of field emission type cold cathodeusing the plating method as shown in the first or second embodiment.However, in the flat type image display device according to thisembodiment, the display is performed without using the gate electrode.

In this flat type image display device, in place of gate line made ofgate electrode layer 54 shown in FIG. 7, transparent anode electrodes 64(anode lines) formed on the glass substrate 61 are arranged in adirection parallel to the paper surface.

Pixel light-up and light-off are selected by arbitrarily setting thepotential between the anode electrode 64 and the emitter 58 forrespective pixels, through the anode line and cathode line. When acertain anode line and a certain cathode line are selected and apredetermined potential is applied to the respective lines, a group ofemitters situated at the intersection of the concerned anode line andcathode line operates, and the luminescent element layer 65 at theposition corresponding to the selected group of emitters lights up.

FIG. 9 shows schematically another example of flat type image displaydevice according to this embodiment. This flat type image display deviceis also manufactured by applying the vacuum micro device as shown in thefourth embodiment (refer to FIG. 6). In other words, it is manufacturedby applying the manufacturing method of field emission type cold cathodeusing the plating method as shown in the first or second embodiment.However, in the flat type image display device according to thisembodiment, the display is performed without using the gate electrode.

In this flat type image display device, there is, so called, a metalback layer 66 consisting of metal thin film layer like Al thin filmlayer formed on the luminescent element layer 65. This metal back layer66 performs as conductive layer for discharging electrons on theluminescent material layer 65 and reflecting emissive light from theluminescent material layer 65. The metal back layer 66 may be used asanode electrodes so that transparent anode electrodes 64 may beeliminated.

In this embodiment, an example using the method as shown in the first orsecond embodiment has been described; however, it is also possible tomanufacture the flat type image display device by applying themanufacturing method of field emission type cold cathode as describedfor the third embodiment.

Embodiment 6

FIG. 10A to FIG. 10D show schematically the manufacturing process offield emission type cold cathode device according to a sixth embodimentof the present invention.

First, as shown in FIG. 10A, a photoresist pattern 112 is formed on ametal substrate (conductive support substrate) 111. Next, likeembodiment 1, Ni—B—P base electroless plating liquid 113, adjusted toabout PH5, is prepared by dissolving about 25 g of nickel sulfate, about40 g of sodium hypophosphite, about log of sodium acetate, about log ofsodium citrate, and about 30 g of boric acid in about 1 litter ofdistillated water. About 50 g of fullerene C₆₀ or carbon nanotube aremixed in this plating liquid.

Thus, the substrate 111 is immersed in the plating solution 113 forabout 3 minutes. As the result, fullerene or carbon nanotube hasprecipitated down to contact with the surface of the substrate 111 andthe photoresist pattern 112, and a Ni—B—P base electroless plating layer(metal plating layer 115) containing fullerene or carbon nanotube isformed on the surface of the substrate 111 and the photoresist pattern112 with a thickness of about 3 μm as shown in FIG. 10B. Then, thephotoresist pattern 112 is eliminated by the stripper solution and themetal plating layer 115 on the photoresist pattern 112 is lift off andeliminated.

Finally, as shown in FIG. 10C (for carbon nanotube 116) or FIG. 10D (forfullerene 117), patterned metal layers 115 are formed on the metalsubstrate 111. The metal substrate can be used as the electrode so thata patterned field emission type cold cathode can be obtained.

Embodiment 7

FIG. 11A and FIG. 11B show schematically the manufacturing process ofvacuum micro device according to a seventh embodiment of the presentinvention. This vacuum micro device is manufactured by applying themanufacturing method of field emission type cold cathode using theplating method as shown in the sixth embodiment.

First, as shown in FIG. 11A, an insulation layer 121 made of SiO₂ or SiNor the like is formed on the field emission type cold cathode substrateincluding patterned metal plating layer 115 containing carbon nanotube116 and metal substrate 111, and further, a gate electrode layer 122made of conductive material such as W is formed thereon. The insulationlayer 122 can be formed by electron beam evaporation method, spatteringmethod, CVD method or others.

Next, as shown in FIG. 11B, the gate electrode layer 122 and theinsulation layer 121 are patterned by lithography technology to formgate electrode and gate wiring. At this time, the metal plating layer115 containing carbon nanotube 116 is exposed in a cavity (concaveportion) 123 surrounded by the insulation film 121 and the gateelectrode 122.

Thus, a vacuum micro device using the carbon nanotube 116 fixed to themetal plating layer 115 as electron emission section is manufactured. Itgoes without saying, a metal plating layer 115 containing fullerene inplace of carbon nanotube may be formed.

Embodiment 8

FIG. 12A to FIG. 12C show schematically the manufacturing process ofvacuum micro device according to an eighth embodiment of the presentinvention.

First, as shown in FIG. 12A, an insulation layer 132 made of SiO₂ or SiNor the like is formed on the metal substrate 131, and further, a gateelectrode layer 133 made of conductive material such as W is formedthereon. The insulation layer 132 can be formed by electron beamevaporation method, spattering method, CVD method or others.

Next, as shown in FIG. 12B, the gate electrode layer 133 and theinsulation layer 132 are patterned by lithography technology to formgate electrode and gate wiring. At this time, the metal substrate 131 isexposed in a cavity (concave portion) 134 surrounded by the insulationfilm 132 and the gate electrode 133.

Next, as shown in FIG. 12C, a metal plating layer 135 containing carbonnanotube 136 is formed on the metal substrate 131, by the electroplatingprocessing as described in the second embodiment.

Thus, a vacuum micro device using the carbon nanotube 136 fixed to themetal plating layer 135 as electron emission section is manufactured. Itgoes without saying, a metal plating layer 135 containing fullerene inplace of carbon nanotube may be formed.

In the respective embodiments mentioned above, examples using Ni—B—Pbase plating layer as metal plating layer have been shown; however, PTFE(polytetrafluoro ethylene) may be added in place of B and P, and in thiscase also, the current emission stability or the like can be enhanced byso-called resistive ballasting effect. In addition, Cr, or Cu or thelike can be used in place of Ni, as metal plating layer. When Ni—B—Pbase plating layer is used for metal plating layer, it is preferable tomake B concentration in the metal plating layer about 3 to 40%, and Pconcentration about 7 to 40%. Besides, when Ni plating layer includingPTFE is used for metal plating layer, it is preferable to make PTFEconcentration in the metal plating layer about 0.1 to 30%.

Also, a metal plating layer made of only metal such as Ni, Cr or Cu maybe used as metal plating layer, without adding B, P or PTFE or similarsubstance. The conductivity of metal plating layer obtained by platingmethod is substantially equivalent to the bulk metal (equal or superiorto about 99% of bulk metal) and superior to the case where the carbonnanotube is formed by printing (about 10 to 20% of bulk), or metal filmsobtained by spattering method (about 30 to 90%). Therefore, imagequality deterioration by signal delay due to the increase of wiringresistance or other problems can be prevented, when a large area flattype image display device is to be manufactured.

In addition, for the metal plating layer obtained by the plating method,it is possible to manufacture with a large thickness such as about 300μm or more, and it is possible to reduce the wiring resistance greatly.On the other hand, for the metal layer obtained by the spatteringmethod, the increase of thickness may cause to peel off the film ordeteriorate the film quality by the inner stress, therefore, inpractice, the film thickness is limited to about 1 to 2 μm or less, andit is difficult to reduce the wiring resistance. As for the thick filmprinting, the film thickness that can be manufactured by a singleprinting is normally limited to about 10 to 50 μm. Consequently, formanufacturing a film equal or superior to several hundreds μm inthickness, it is necessary to anneal each time it is printed, provokingthe deterioration of carbon nanotube.

Besides, in the foregoing respective embodiment, the curvature radius offullerene and carbon nanotube tip portion is made about 100 nm or less,preferably about 50 nm or less, more preferably about 30 nm or less, andstill more preferably about 15 nm or less.

In addition, in the foregoing embodiment, the metal plating layer isformed using plating liquid containing fullerene and carbon nanotube;however, the metal plating layer can be formed using plating liquidcontaining carbon base field emission material (carbon, graphite,diamond), metal fine particle (Mo, Ta, W, Ni, Cr, Au, Ag, Pd, Cu, Al,Sn, Pt, Ti, Fe), semiconductor fine particle (Si), low work functionmaterial fine particle of 4 eV or less in work function (LaB₆, beta W,SiC, Al₂O₃, aluminum boride (9Al₂O₃.2B₂O₃), potassium titanate), ornegative electron affinity (NEA) material fine particle (diamond, AlN,GaN, TiN, TiC, AlGaN), in place of fullerene and carbon nanotube.

Moreover, in addition to the aforementioned applications, the fieldemission type cold cathode device according to the present invention canbe used for vacuum micro power device, environmental resistant device(space device, nuclear power device, extreme environmental resistantdevice (radiation resistant device, high temperature resistant device,low temperature resistant device)), various sensors, or others.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1-13. (canceled)
 14. A manufacturing method of field emission type coldcathode devices comprising: immersing a substrate on which a cathodeline is formed in a plating liquid containing at least one carbonstructure selected from a group of fullerene and carbon nanotube; andforming a metal plating layer along a top surface of said cathode lineby electroplating processing or electroless plating processing, saidmetal plating layer having a substantially uniform thickness andcontaining said carbon structure, said carbon structure being stuck outfrom said metal plating layer and a part of said carbon structure beingburied in said metal plating layer. 15-18. (canceled)
 19. Themanufacturing method according to claim 14, wherein forming said metalplating layer includes forming said metal plating layer along top andside surfaces of said cathode line.
 20. The manufacturing methodaccording to claim 14, wherein said metal plating layer is formed byelectroplating processing, and said carbon nanotube stuck out from saidmetal plating layer is perpendicular to the top surface of said cathodeline.
 21. The manufacturing method according to claim 14, wherein saidmetal plating layer is selected from a group of nickel, chromium andcopper.
 22. A manufacturing method of field emission type cold cathodedevice comprising: forming a cathode line on a substrate; and forming ametal plating layer along a top surface of said cathode line byelectroplating processing or electroless plating processing, said metalplating layer having a substantially uniform thickness and containing atleast one carbon structure selected from a group of fullerene and carbonnanotube, said carbon structure being stuck out from said metal platinglayer and a part of said carbon structure being buried in said metalplating layer.
 23. The manufacturing method according to claim 22,wherein forming said metal plating layer includes forming said metalplating layer along top and side surfaces of said cathode line.
 24. Themanufacturing method according to claim 22, wherein said metal platinglayer is formed by electroplating processing, and said carbon nanotubestuck out from said metal plating layer is perpendicular to the topsurface of said cathode line.
 25. The manufacturing method according toclaim 22, wherein said metal plating layer is selected from a group ofnickel, chromium and copper.
 26. A manufacturing method of vacuum microdevice comprising: forming a cathode line on a substrate; forming ametal plating layer along a top surface of said cathode line byelectroplating processing or electroless plating processing, said metalplating layer having a substantially uniform thickness and containing atleast one carbon structure selected from a group of fullerene and carbonnanotube, said carbon structure being stuck out from said metal platinglayer and a part of said carbon structure being buried in said metalplating layer; and forming an electrode disposed separately from saidsubstrate, said electrode having applied thereto a higher electricalpotential than an electrical potential applied to said metal platinglayer.
 27. The manufacturing method according to claim 26, whereinforming said metal plating layer includes forming said metal platinglayer along top and side surfaces of said cathode line.
 28. Themanufacturing method according to claim 26, wherein said metal platinglayer is formed by electroplating processing, and said carbon nanotubestuck out from said metal plating layer is perpendicular to the topsurface of said cathode line.
 29. The manufacturing method according toclaim 26, wherein said metal plating layer is selected from a group ofnickel, chromium and copper.
 30. A manufacturing method of vacuum microdevice comprising: forming a cathode line on a first substrate; forminga metal plating layer along a top surface of said cathode line byelectroplating processing or electroless plating processing, said metalplating layer having a substantially uniform thickness and containing atleast one carbon structure selected from a group of fullerene and carbonnanotube, said carbon structure being stuck out from said metal platinglayer and a part of said carbon structure being buried in said metalplating layer; forming an electrode on a second substrate, saidelectrode having applied thereto a higher electrical potential than anelectrical potential applied to said metal plating layer; forming aluminescent material on said electrode; and arranging said firstsubstrate and said second substrate in a face-to face relation.
 31. Themanufacturing method according to claim 30, wherein forming said metalplating layer includes forming said metal plating layer along top andside surfaces of said cathode line.
 32. The manufacturing methodaccording to claim 30, wherein said metal plating layer is formed byelectroplating processing, and said carbon nanotube stuck out from saidmetal plating layer is perpendicular to the top surface of said cathodeline.
 33. The manufacturing method according to claim 30, wherein saidmetal plating layer is selected from a group of nickel, chromium andcopper.